Step-by-step variable resistor assembly

ABSTRACT

A step-by-step variable resistor assembly of compact and simplified construction essentially comprising an operating shaft, a mounting panel and base plate connected with each other in spaced relation to each other, both rotatably carrying the operating shaft, a tap member carried by the operating shaft within a space between the mounting panel and the base plate, a detent device for providing detent positions for rotation of the operating shaft, terminal members of the number corresponding to the number of the detent position, and a film of resistance material arranged in a substantially split-ring shape and electrically connecting the terminal members. Upon rotation of the operating shaft to any one of the detent positions, some or all of the terminal members are shortcircuited to give a definite value of resistance.

Kohima [11] 3,832,671 Aug. 27, 1974 STEP-BY-STEP VARIABLE RESISTOR ASSEMBLY Tatsuo Kohima, Kyoto, Japan Murata Manufacturing Co., Ltd., Kyoto-fu, Japan Filed: Jan. 24, 1973 Appl. No.: 326,522

Inventor:

Assignee:

Foreign Application Priority Data May 12, 1972 Japan 47-559l8[U] US. Cl. 338/188, 338/190 References Cited UNITED STATES PATENTS 5/1933 Douglas 338/191 X 3/1953 Aust et a1. 338/190 X 22 2| I00 II Primary Examiner-J. V. Truhe Assistant Examiner-David A. Tone Attorney, Agent, or Firm-Craig & Antonelli ABSTRACT A step-by-step variable resistor assembly of compact and simplified construction essentially comprising an operating shaft, a mounting panel and base plate connected with each other in spaced relation to each other, both rotatably carrying the operating shaft, a tap member carried by the operating shaft within a space between the mounting panel and the base plate, a detent device for providing detent positions for rotation of the'operating shaft, terminal members of the number corresponding to the number of the detent position, and a film of resistance material arranged in a substantially split-ring shape and electrically connecting the terminal members. Upon rotation of the operating shaft to any one of the detent positions, some or all of the terminal members are shortcircuited to give a definite value of resistance.

8 Claims, 6 Drawing Figures 23 I7 I20 B!) If) 4 STEP-BY-STEP VARIABLE RESISTOR ASSEMBLY 3 able resistor assembly having a detent device for movement of a tap step-by-step engageable with any of a pluralityof equidistantly spaced lead-out terminals disposed on and in connection with a film of resistance material.

Heretofore, a variable resistor assembly of similar type to the one herein disclosed employs a plurality of commercially available resistor elements disposed between each two of the lead-out terminals by the use of lead wires. This typical, conventional variable resistor assembly has some disadvantages. One of them is that mounting of the resistor elements is so troublesome as to incur the increase of manufacturing processes and, for example, if a certain number of the resistor elements are employed, soldering operation is required in a number of time corresponding to twice the number of the resistor elements employed. In addition, because each of the resistor elements is relatively large in size, the number of the resistorelements to be used in one variable resistor assembly is naturally limited and/or production of a step-by-step variable resistor assembly of compact and simplified construction particularly intended for use in association with transistorized electrical and/or electronic instruments having [C and/or LSI circuit components is often hampered.

Furthermore, according to the conventional variable resistor assembly, in view of the fact that connection between the resistor elementsand the lead-out terminals is usually made by the use of lead wires, each pair of which extend from both ends of individual resistor elements, the stability of an electric circuit will lose at high frequencies due to stray load losses if it is particularly used in association with attenuators.

Accordingly, an essential object of the present invention is to provide a step-by-step variable resistor assembly of compact and simplified construction, substantially eliminating the disadvantages inherent in the conventional resistor assembly of the similar type.

Another important object of the present invention is to provide a step-by-step variable resistor of the above mentioned type which does not substantially incur the stray load losses at the high frequencies and is, therefore, particularly suitable for use in association with the attenuators.

A further object of the present invention is to provide a step-by-step variable resistor of the above mentioned type which can be manufactured at lower costs than required in the conventional resistor assembly of the similar type, and without substantially requiring an additional step of manufacture.

A still further object of the present invention is to provide a step-by-step variable resistor assembly which is reliable in performance and durable for a substantially long period of service.

According to the present invention, the step-by-step variable resistor assembly essentially comprises an operating shaft, a detent device for providing a plurality of detent positions for rotation of said operating shaft, a tap member rigidly carried by said operating shaft, a base plate having equidistantly spaced lead-out tenninals of the number corresponding to the number of the detent positions provided by said detent device and a film of resistance material plated on the base plate in a substantially split-ring shape and connected with the lead-out terminals, said tap member upon rotation of the operating shaft being selectively engageable with any of the lead-out terminals.

These and other objects and features of the present invention will become apparent from the following description taken in conjunction with preferred embodiments thereof with reference to the accompanying drawings, in which;

FIG. 1 is a side elevational view of a step-by-step variable resistor assembly according to one embodiment of the present invention,

FIG. 2 is a similar view to FIG. 1, but shown in section,

FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 1,

FIG. 4 is a bottom plan view of the resistor assembly of FIG. 1, v

FIG. 5 is a side elevational view of the step-by-step variable resistor assembly according to another embodiment of the present invention, and

FIG. 6 is a cross-sectional view taken along the line VI-VI in FIG. 5, with a portion thereof being broken away.

Referring first to FIGS. 1 to 4, the step-by-step variable resistor assembly comprises a mounting panel member 10 formed at a substantially central portion with an opening 10a through which a bearing sleeve 11 extends. This bearing sleeve 11 has one end suitably rigidly secured to said panel member 10, the outer pe-' ripheral surface of which is threaded as at 11a for the purpose of mounting the resistor assembly of the present invention to an instrument panel or the like to which it is to be fitted in any known manner.

A base plate 12, made of electrically insulating material and preferably of the same size as the panel member 10, is carried by said panel member 10 in spaced relation with respect to each other by means of a plurality of bolts and nuts, generally indicated by 13, with the corresponding number of spacer bushings 14 mounted on the bolts between said panel member 10 and said base plate 12. The base plate is formed with a circular opening 12a in coaxial relation to the longitudinal axis of the bearing sleeve 11.

A rotor 15, made of electrically insulating material and having preferably the same thickness as the base plate 12, is situated within the circular opening 12a and non-rotatably mounted on an operating shaft 18 which rotatably extends through the bearing sleeve 11. As clearly shown, the operating shaft 18 has a free end adapted to rigidly receive an operating knob (not shown) accessible to an operator of the variable resistor assembly and the other end portion substantially flattened with a step formed as at 18a. While the operating shaft 18 is constructed as such, the rotor 15 is formed at its central portion with an opening 15a of substantially the same size as the cross-sectional area of the flatened portion of said operating shaft 18, which opening 15a receives therein the flatened portion of the operating shaft 18 for rotation together with the operating shaft 18. It is-to be noted that the operating shaft- 18 is held in position by means of a pair of stoppers 19a and 19b, which may be in the form of snap rings or pin members, rigidly secured or otherwise mounted on said operating shaft 18 without permitting the latter to axially slide relative to the mounting panel member 10.

The rotor 15'has a first surface opposing to the panel member and carrying thereon an annular tap member 16, as shown in FIG. 4, having a segmental outward projection 16a. This annular tap member 16 may be secured tosaid rotor in any suitable manner. However, in the instance as shown, the annular tap member 16 is provided integrally with a plurality of nail members 16b which extend through the rotor 15 and radially outwardly inwardly bent on a second surface of said rotor facing the panel member 10, whereby said annular tap member 16 is non-detachably carried by said rotor 15. In order to avoid a possible separation of the rotor 15 from the circular opening 12a, an insulator plate or disc 17 of a diameter preferably greater than that of the circular opening 12a may be interposed between the second surface of the rotor 15 and the bent portions of the nail members 1612 of the annular tap member 16 unless otherwisemounting of the rotor 15 on the flatened portion of the operating shaft 18 is made rigidly such as by the use of bonding material or the like.

With particular reference to FIGS. 3 and 4, the base plate 12 is provided on one surface thereof, flush with the first surface of the rotor 15, with a plurality of leadout terminals T T T and T arranged-in equidistantly spaced relation with respect to one another and concentrically with respect to the annular tap member 16. These lead-out terminals T T T and T may be rigidly secured to the base plate 12 by the use of the corresponding number of pin members 1 t t and t each extending through the base plate 10 and having both ends flatened by any suitable method, for example, by means of caulking. It is to be noted that one of the lead-out terminals, such as indicated by T is made to constantly slidably engage the annular tap member 16 while the segmental projection 16a of said tab member 16 is made to selectively engage any one of the remaining lead-out terminals T T T and T upon rotation of the operating shaft 18.

A film of resistance material is coated on the other surface of the base plate 12 in a substantially split-ring shape as clearly shown in FIG. 3. The film of resistance material 20 has one end connected with the lead-out terminal T, and the other end connected with the leadout terminal T while a substantially intermediate portion of said resistance film 20 connects the remaining lead-out terminals T T T and T with a disconnecting space 20a formed between the both ends of said resistance film 20, i.e., between the lead-out terminals T and T Coating of the resistance film 20 on the other surface of the base plate 12 may be effected prior to mounting of the lead-out terminals on the base plate,

and vice versa.

Referring back to FIGS. 1 and 2, in order to enable the segmental projection 16a of the annular tap member 16 to selectively engage any one of the lead-out terminals T T T and T upon rotation of the operating shaft 18, the detent device is employed for providing detent positions of the number corresponding to rality of fingers 21a, the number of which preferably corresponds to that of the lead-out terminals T T T-, and T As clearly shown, these fingers 21a are rounded or otherwise tapered and downwardly extend through a plurality of segmental openings (not shown) formed in the panel member 10, with each space between the fingers 21a of individual pairs situating at a position corresponding to any of the lead-in terminals.

The plate member 21 may be omitted, in which case the fingers 21a must be provided by subjecting the panel member 10 to a press work or blanking technique. Alternatively, a rivetting technique may be employed to provide the fingers 21a. I

Non-rotatably mounted on the flattened portion of the operating shaft 18 within a space between the mounting panel member 10 and the base plate 12 is a carrier disc 22 formed with a bearing opening 22a 10- cating immediately below each finger 21a. This carrier disc 22 is elastically biased towards the step 18a on the operating shaft 18 by a spring washer 23 mounted on the flattened portion of the operating shaft 18 between said carrier disc 22 and the stopper 19b.

The-detent device further comprises a detent ball 24 rotatably accommodated within the bearing opening 22a of the carrier disc 22 such as to permit the step-bystep rotation of the carrier disc 22 and, thus, the operating shaft 18. It is to be noted that the spring washer 23 is so deformable as to permit the detent ball 24 to retract when the latter is tended to roll over any of the fingers 21a.

In the arrangement so far described, the operating shaft 18 can be indefinitely rotatable in either of the opposed directions. In the case where it is undesirable, a rotation control may be provided for rotation of the operating shaft 18 and, thus, the segmental projection 16a of the annular tap member 16 about the longitudinal axis of said operating shaft 18, whereby the operating shaft can be rotatable through a predetermined angle from a position in which the segmental projection 16a engages the lead-out terminal T to another position in which the segmental projection 16a engages the lead-out terminal T without permitting said projection 16a to pass through the space between the lead-out terminals T, and T This rotation control may comprise an engagement 25 integrally formed with or otherwise rigidly secured to the carrier disc 22 and a barrier piece (not) shown) integrally formed with or otherwise rigidly secured to the mounting panel member 10, said engagement 25 being engageable to said barrier piece from both sides. Preferably, the barrier piece has a width corresponding to the space between the lead-out terminals T, and T The operation of the step-by-step variable resistor assembly of the construction as shown in FIGS. 1 to 4 is self-explanatory. Assuming that the operating shaft 18 is manually rotated such as to permit the segmental projection 16a of the annular tap member 16 to engage the lead-out terminal T as shown in FIG. 4, the resistance defined between the lead-out terminals T, to T is shortcircuited via the annular tap member 16 and, accordingly, the setting of the variable resistor is represented by the resistance between the lead-out terminals T6 IO According to another embodiment of the present invention shown in FIGS. 5 and 6, the ends of the pin members t t and t which are situated in the Referring now to FIGS. 5 and 6, the base platel2 is formed with a bearing opening 12a for rotatably receiving therein the operating shaft 18. The bridge member 30 is mounted on the flattened portion of the operating shaft 18 for rotation together with the latter and biased towards the step 18a by a bushing 31 mounted on the operating shaft 18 and between the base plate and the bridge member 30.

The bridge member 30 is made of metallic material having a sufficient resiliency and has the short feeler 30a elastically in constant contact with an annular conductor 32 secured to the surface of the base plate 12 in coaxial relation to the longitudinal axis of the operating shaft 18 and electrically connected with a tap tenninal 32a. The longer feeler 30b of the bridge member 30 is elastically biased such as to permit the tip of said feeler 30b in contact with the surface of the base plate 12 and adapted to selectively engage any one of the pin members t t t and t To provide a detent position for the rotation of the bridge member 30 and, thus, the operating shaft 18, the end of each of the pin members t t t and t which faces towards the mounting panel member 10, is innerwardly rounded or' recessed so that the tip of the long feeler 30b is collapsibly received therein.

lt seems undesirable to permit the tip of the feeler 30b to slide in contact with the film of resistance material 20. To avoid this, as clearly shown in FIG. 6, each of the pin members is provided with a lug, generally indicated by 33, which is covered by the resistance film 20 and serves as an electrical connection between said resistance film 20 and the corresponding pin members while the latter is arranged outside the resistance film 20, but substantially in alignment with the circular path of travel of the tip of the long feeler 30b.

In the embodiment shown in FIGS. 5 and 6, it is to be noted that the lead-out terminals T T T and T may be situated on the same plane as the resistance film 20, in which case the lugs 33 may be omitted, should each of radially inwardly oriented ends of said lead-out terminals be extended to the resistance film 20.

Although the present invention has been fully disclosed in conjunction with the preferred embodiments thereof, it is to be noted that various changes and modifications are apparent to those skilled in the art. By way of example, the detent device which may be employed in the present invention may be of a leaf spring detent type which comprises a leaf spring having a roller element carried thereby and a star wheel rigidly mounted on the operating shaft and having a plurality of radially inwardly rounded recesses along the peripheral edge of said star wheel for collapsibly receiving therein said roller element biased by the leaf spring.

Accordingly, unless otherwise such changes and modifications depart from the true spirit and scope of the present invention, they should be construed as included within such spirit and scope of the present invention.

What is claimed is:

o 1. A step-by-step variable resistor assembly comprising a manually rotatable operating shaft; means for providing a plurality of detent positions for rotation of said operating shaft; means for rotatably supporting said operating shaft; a base plate rigidly suspended by said supporting means in spaced relation with respect to said supporting means; a film of resistance material provided in said base plate in substantially coaxial relation with respect to the axis of rotation of said operating shaft; terminal members of the number at least corresponding to that of said detent positions provided by said detent means and electrically connected with said film of resistance material; and means responsive to the positioning of said operating shaft to selectively shortcircuit between some or all of said terminal members, said supporting means including a mounting panel member having a central opening through which said operating shaft rotatably extends and supported thereby and a plurality of segmental openings arranged in substantially coaxial relation with respect to the axis of rotation of said operating shaft, said detent means including a plate member having a plurality of fingers bent to extend through said segmental openings and situated within a space between said panel member and said base plate, a carrier disc rigidly carried by said operating shaft, a detent ball rotatably carried by said carrier disc, and a spring element rigidly carried by said operating shaft and elastically biasing said detent ball so as to permit said detent ball, while rotatably carried by said carrier disc, to be received in a space between said fingers of each adjacent pair, said spring element being deformable so as to retract said detent ball and then to permit said detent ball to relatively roll over each of said fingers when said operating shaft is rotated.

2. A step-by-step variable resistor assembly as claimed in claim 1, wherein said spring element is a spring washer having a central bore through which said operating shaft extends.

3. A step-by-step variable resistor assembly as claimed in claim 1, wherein said supporting means further includes a bearing sleeve rigidly mounted on said mounting panel member for steadily rotatably supporting said operating shaft and a nut member threadably mounted on said sleeve for fastening said plate member in position.

4. A step-by-step variable resistor assembly as claimed in claim 1, wherein means responsive to the positioning of said operating shaft comprises a rotor of a thickness substantially equal to that of said base plate and rotatably housed in a corresponding opening centrally formed in said base plate, and an annular tap member mounted on said rotor in coaxial relation with respect to the axis of rotation of said operating shaft and having a substantially segmental projection selectively engageable with any one of said terminal members in response to the positioning of said operating shaft.

5. A step-by-step variable resistor assembly as claimed in claim 1, wherein said film of resistance material is arranged in a substantially split-ring shape thereby providing an electrically disconnecting space between an adjacent pair of said terminal members.

6. A step-by-step variable resistor assembly as claimed -in claim 1, wherein said film of resistance material is arranged in a substantially split-ring shape and further comprising a rotation control for restricting the operating shaft to rotate through a predetermined angle corresponding to the space between both ends of said film of resistance material.

7. A step-by-step variable resistor assembly comprising a manually rotatable operating shaft; means for providing a plurality of detent positions for rotation of said operating shaft; means for rotatably supporting said operating shaft; a base plate rigidly suspended by said supporting means in spaced relation with respect to said supporting means; a film of resistance material provided in said base plate in substantially coaxial relation with respect to the axis of rotation of said operating shaft; terminal members of the number at least corresponding to that of said detent positions provided by said detent means and electrically connected with said film of resistance material; and means responsive to the positioning of said operating shaft to selectively shortcircuit between some or all of said terminal members, said supporting means including a mounting panel member having a central opening through which said operating shaft rotatably extends and supported thereby, said detent means including a bridge member having a pair of short and long feelers radially outwardly extending therefrom, said bridge member being non-rotatably carried by said operating shaft while either of said feelers is constantly slidably engaged with an annular terminal member mounted on said base plate in coaxial relation with respect to the axis of rotation of said operating shaft and the other feeler is selectively engageable with any one of the other terminal members, each of said other terminal members including a pin provided with a recessed end portion for collapsibly receiving the end portion of the other feeler therein.

8. A step-by-step variable resistor assembly as claimed in claim 7 wherein said film of resistance mate rial is arranged in a substantially split-ring shape thereby providing an electrically disconnecting space between an adjacent pair of said pins, said pins being positioned outside of the path of said film of resistance material and said other terminal members including a lug member for a respective pin disposed on said base plate and covered with the resistance film for electrically connecting said resistance film and said corresponding pin. 

1. A step-by-step variable resistor assembly comprising a manually rotatable operating shaft; means for providing a plurality of detent positions for rotation of said operating shaft; means for rotatably supporting said operating shaft; a base plate rigidly suspended by said supporting means in spaced relation with respect to said supporting means; a film of resistance material provided in said base plate in substantially coaxial relation with respect to the axis of rotation of said operating shaft; terminal members of the number at least corresponding to that of said detent positions provided by said detent means and electrically connected with said film of resistance material; and means reSponsive to the positioning of said operating shaft to selectively shortcircuit between some or all of said terminal members, said supporting means including a mounting panel member having a central opening through which said operating shaft rotatably extends and supported thereby and a plurality of segmental openings arranged in substantially coaxial relation with respect to the axis of rotation of said operating shaft, said detent means including a plate member having a plurality of fingers bent to extend through said segmental openings and situated within a space between said panel member and said base plate, a carrier disc rigidly carried by said operating shaft, a detent ball rotatably carried by said carrier disc, and a spring element rigidly carried by said operating shaft and elastically biasing said detent ball so as to permit said detent ball, while rotatably carried by said carrier disc, to be received in a space between said fingers of each adjacent pair, said spring element being deformable so as to retract said detent ball and then to permit said detent ball to relatively roll over each of said fingers when said operating shaft is rotated.
 2. A step-by-step variable resistor assembly as claimed in claim 1, wherein said spring element is a spring washer having a central bore through which said operating shaft extends.
 3. A step-by-step variable resistor assembly as claimed in claim 1, wherein said supporting means further includes a bearing sleeve rigidly mounted on said mounting panel member for steadily rotatably supporting said operating shaft and a nut member threadably mounted on said sleeve for fastening said plate member in position.
 4. A step-by-step variable resistor assembly as claimed in claim 1, wherein means responsive to the positioning of said operating shaft comprises a rotor of a thickness substantially equal to that of said base plate and rotatably housed in a corresponding opening centrally formed in said base plate, and an annular tap member mounted on said rotor in coaxial relation with respect to the axis of rotation of said operating shaft and having a substantially segmental projection selectively engageable with any one of said terminal members in response to the positioning of said operating shaft.
 5. A step-by-step variable resistor assembly as claimed in claim 1, wherein said film of resistance material is arranged in a substantially split-ring shape thereby providing an electrically disconnecting space between an adjacent pair of said terminal members.
 6. A step-by-step variable resistor assembly as claimed in claim 1, wherein said film of resistance material is arranged in a substantially split-ring shape and further comprising a rotation control for restricting the operating shaft to rotate through a predetermined angle corresponding to the space between both ends of said film of resistance material.
 7. A step-by-step variable resistor assembly comprising a manually rotatable operating shaft; means for providing a plurality of detent positions for rotation of said operating shaft; means for rotatably supporting said operating shaft; a base plate rigidly suspended by said supporting means in spaced relation with respect to said supporting means; a film of resistance material provided in said base plate in substantially coaxial relation with respect to the axis of rotation of said operating shaft; terminal members of the number at least corresponding to that of said detent positions provided by said detent means and electrically connected with said film of resistance material; and means responsive to the positioning of said operating shaft to selectively shortcircuit between some or all of said terminal members, said supporting means including a mounting panel member having a central opening through which said operating shaft rotatably extends and supported thereby, said detent means including a bridge member having a pair of short and long feelers radially outwardly extending therefrom, said bridge member being non-rotatably carried by said operating shaft while either of said feelers is constantly slidably engaged with an annular terminal member mounted on said base plate in coaxial relation with respect to the axis of rotation of said operating shaft and the other feeler is selectively engageable with any one of the other terminal members, each of said other terminal members including a pin provided with a recessed end portion for collapsibly receiving the end portion of the other feeler therein.
 8. A step-by-step variable resistor assembly as claimed in claim 7 wherein said film of resistance material is arranged in a substantially split-ring shape thereby providing an electrically disconnecting space between an adjacent pair of said pins, said pins being positioned outside of the path of said film of resistance material and said other terminal members including a lug member for a respective pin disposed on said base plate and covered with the resistance film for electrically connecting said resistance film and said corresponding pin. 